Push the button for adjustment on the work piece. Fine adjustment for optimum adaptation to different sizes of work pieces and a comfortable handle width. Self-locking on pipes and nuts: no slipping on the work piece and low hand force required. Gripping surfaces with special hardened teeth, teeth hardness approx. 61 HRC: high wear resistance and stable gripping. Box-joint design for high stability due to double guide. Reliable catching of the hinge bolt: no unintentional shifting. Pinch guard prevents operators’ fingers being pinched. Chrome vanadium electric steel, forged, multi-stage oil-hardened. Made in Germany.